/*
 * Copyright 1999-2012 Alibaba Group.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
/**
 * (created at 2011-1-23)
 */
package fm.liu.timo.parser.ast.expression.primary.function.string;

import java.util.ArrayList;
import java.util.List;
import fm.liu.timo.parser.ast.expression.Expression;
import fm.liu.timo.parser.ast.expression.primary.function.FunctionExpression;
import fm.liu.timo.parser.visitor.Visitor;

/**
 * @author <a href="mailto:shuo.qius@alibaba-inc.com">QIU Shuo</a>
 */
public class Trim extends FunctionExpression {
    public static enum Direction {
        /** no tag for direction */
        DEFAULT, BOTH, LEADING, TRAILING
    }

    private final Direction direction;

    private static List<Expression> wrapList(Expression str, Expression remstr) {
        if (str == null)
            throw new IllegalArgumentException("str is null");
        List<Expression> list =
                remstr != null ? new ArrayList<Expression>(2) : new ArrayList<Expression>(1);
        list.add(str);
        if (remstr != null)
            list.add(remstr);
        return list;
    }

    public Trim(Direction direction, Expression remstr, Expression str) {
        super("TRIM", wrapList(str, remstr));
        this.direction = direction;
    }

    /**
     * @return never null
     */
    public Expression getString() {
        return getArguments().get(0);
    }

    public Expression getRemainString() {
        List<Expression> args = getArguments();
        if (args.size() < 2)
            return null;
        return getArguments().get(1);
    }

    public Direction getDirection() {
        return direction;
    }

    @Override
    public FunctionExpression constructFunction(List<Expression> arguments) {
        throw new UnsupportedOperationException("function of trim has special arguments");
    }

    @Override
    public void accept(Visitor visitor) {
        visitor.visit(this);
    }
}
